Think tank The UK in a Changing Europe said Britons were unlikely to change their minds about leaving the EU, despite the political and economic uncertainty it has brought, because attitudes are becoming more entrenched.

“The (Brexit) referendum highlighted fundamental divisions in British society and superimposed a leave-remain distinction over them. This has the potential to profoundly disrupt our politics in the years to come,” said Anand Menon, the think tank’s director.

Britain is negotiating a deal with the EU which will shape future trade relations, breaking with the bloc after four decades, but the process is complicated by the divisions within parties, society and the government itself.

Menon said the research, based on a series of polls over the 18-month period since Britain voted to leave the European Union, showed 35 percent of people self-identify as “Leavers” and 40 percent as “Remainers”.

Research also found that both sides had a tendency to interpret and recall information in a way that confirmed their pre-existing beliefs which also added to the deepening of the impact of the vote.

The differences showed fragmentation was more determined by age groups and location than by economic class.

Polls have shown increasing support for a second vote on whether or not to leave the European Union once the terms of departure are known, but such a vote would not necessarily provide a different result, a poll by ICM for the Guardian newspaper indicated last week.

The report also showed that age was a better pointer to how Britons voted than employment. Around 73 percent of 18 to 24-year-olds voted to stay in the EU, but turnout among that group was lower than among older voters.

“British Election Study surveys have suggested that, in order to have overturned the result, a startling 97 percent of under-45s would have had to make it to the ballot box, as opposed to the 65 percent who actually voted,” the report said.

The difference between generations became even more pronounced in the 2017 general election, when the largest gap in how different generations voted was measured in Britain.

The British Election Study has been conducted by academics at every general election since 1964 and looks at why people vote, and why they vote the way they do.